Recently, air conditioners provided with a heat-pump type refrigerant circulatory system (referred as refrigeration cycle system hereafter) are rapidly coming into wide-spread use not only for cooling but also heating. Heating with such an air conditioner apparatus has conventionally been convective, in which warm air heated by the air conditioner is exhausted to the room.
Also, stoves such as oil or gas stoves have been used for heating. The stoves operate mainly by radiant heating.
A conventional heat-pump type air conditioner is typically shown in FIG. 1. In FIG. 1, the air conditioner has an outdoor unit 20 and an indoor unit 21. Outdoor unit 20 includes a compressor 22, a four way valve 23, an outdoor heat exchanger 24, an outdoor fan 25 and a pressure reducing device such as an expansion valve 26. Indoor unit 21 includes an indoor heat exchanger 27 and an indoor fan 28.
Compressor 22 is connected to outdoor heat exchanger 24, expansion valve 26 and indoor heat exchanger 27 through four-way valve 23. Four-way valve 23 is provided for controlling the direction of flow of refrigerant so that compressor 22, outdoor heat exchanger 24, expansion valve 26 and indoor heat exchanger 27 constitute a cooling cycle or a heating cycle, as described later. Outdoor fan 25 and indoor fan 28 are mounted adjacent to outdoor heat exchanger 24 and indoor heat exchanger 27, respectively.
In a cooling operation, four-way valve 23 is set to cause flow refrigerant to flow in the direction of solid lines, as shown in the drawing, to form the cooling cycle. The refrigerant discharged from compressor 22 flows circularly through one path of four-way valve 23, outdoor heat exchanger 24, expansion valve 26, indoor heat exchanger 27 and the other path of four-way valve 23 in turn.
Indoor heat exchanger 27, therefore, operates as an evaporator of the refrigerant so that it is cooled. In contrast, outdoor heat exchanger 24 operates as a condenser of the refrigerant so that it is heated. As a result, heat in the room is absorbed by the refrigerant in indoor heat exchanger 27 and then transmitted to outdoor heat exchanger 24. Heat of the refrigerant is then transferred to the outdoor air through OutdoOr heat exchanger 24. The air conditioner thus cools objects or persons through a convection of the cooled air.
In a heating operation, four-way valve 23 is set to cause the refrigerant to flow in the direction of broken lines, as shown in the drawing, to form a heating cycle. The refrigerant discharged from compressor 22 flows circularly through one path of four-way valve 23, indoor heat exchanger 24, expansion valve 26, outdoor heat exchanger 27 and the other path of four-way valve 23 in turn.
Indoor heat exchanger 27, therefore, operates as a condenser of the refrigerant so that it is heated or warmed. In contrast, outdoor heat exchanger 24 operates as an evaporator of the refrigerant so that it is cooled. As a result, heat from outside is absorbed by the refrigerant in outdoor heat exchanger 24 and then transmitted to indoor heat exchanger 27. Heat of the refrigerant is then transfered to air inside the room through indoor heat exchanger 27. The air conditioner thus heats. Objects or persons indoors through the convection of warm air.
The air conditioner, i.e., the convective heating by the air conditioner, is superior for warming the whole room. However, convective heating has a disadvantage of creating drafts. Further the convective heating has another disadvantage in that persons feel a rather cool heating in comparison to radiant heating by stoves and the like because the output air is sometimes lower than skin temperature. Convective heating is also inferior to radiant heating when rapid heating is desired.
Accordingly, there has been developed a heat-pump type air conditioner which is provided with not only an indoor heat exchanger for warming air but also g heat radiation panel such as disclosed in Japanese Patent Disclosure No. P55-8570. Indoor heat exchanger is mounted in indoor unit, and heat radiation panel is mounted in front of indoor unit. Heat radiation panel has refrigerant pipes installed on its rear surface.
Heat radiation panel radiates heat due to the high temperature of refrigerant flowing in the pipes. As a result, persons facing heat radiation panel can enjoy a remarkable heating.
Convective heating and radiant heating, however, have not been properly used in the conventional air conditioners. That is, radiant heating always occurs simultaneously with convective heating. Therefore, convective heating and radiant heating could not exhibit sufficiently their features for offering comfortable heating. Also, the compressor in the conventional air conditioner always operates at the same capacity, wasting energy.
This invention is made in view of the above-mentioned circumstances for offering comfortable heatings by performing properly convective heating and radiant heating in an energy-efficient manner.